The long term objective of this proposal is to develop a commercial subunit vaccine against MV infection. Because of the high cost of preparing the surface antigens, a means for achieving an enhanced immune response is an important objective and is the focus of this proposal. Biocompatible and biodegradable microspheres consisting of a copolymer of DL-lactide and glycolide (poly DL-lactide-co- lactide) will be utilized to incorporate MV antigens into small spherical particles (l-l0um). Microspheres containing viral antigens will be used for subcutaneous, intranasal and oral immunization of mice, and the immune response will be evaluated. Another group of mice will be similarly immunized with inactivated virus in solution for comparison. If significant enhancement in the protective immune response is observed using microencapsulated MV antigens, more detailed studies will be pursued subsequently. Studies will also be conducted to understand the mechanism of protection (cellular/antibody mediated) and the duration of such response. Ultimately, a microencapsulated measles virus vaccine will be utilized in clinical field trials for immunoprophylaxis against measles infection.